MAX陶瓷抗热震和耐烧蚀性能及其机制研究

MAX陶瓷具有不同于传统高温陶瓷的异常热震行为及最近发现的裂纹自愈合和耐烧蚀性能，是氧化和高温环境下服役的关键部件的优选材料，但其异常热震行为及耐烧蚀机制一直没有得到合理的解释。本项目以Ti2AlC和Cr2AlC两种代表性的 MAX陶瓷为研究对象，在前期有启发性的实验结果基础上，集中研究材料的抗热震和耐烧蚀性能。主要研究内容包括：确定关键工艺参数，制备具有组织-性能可调的Ti2AlC和Cr2AlC单一材料及新型高温复合材料，对比研究单一和复合材料的高温性能（氧化、热震及烧蚀）。研究关键影响因素如淬冷介质、高温反应产物、微观组织等对材料抗热震性能的影响；研究烧蚀产物、液相形成、氧化层结构、微观组织以及第二相颗粒等对烧蚀性能的影响。本项目旨在揭示MAX材料的耐烧蚀机制及困扰人们近17年的异常热震行为机制。本项目的开展，能取得创新性成果，对促进MAX材料在氧化和高温环境中的应用有推动作用。

MAX ceramics have abnormal thermal shock resistance, crack healing ability and good ablation resistance, which make these materials potential candidates in key components for oxidizing and high temperature environment applications. However, the main mechanisms of their abnormal thermal shock resistance and ablation resistance have not been revealed yet. This project focuses on the investigation of the thermal shock and ablation resistances of Ti2AlC and Cr2AlC as two representative members of MAX ceramics, based on the previous research and enlightening results. The main contents include: firstly, confirming key processing parameters to prepare Ti2AlC and Cr2AlC materials with tunable microstructure-performance and to synthesize MAX-based high temperature composites as well as to compare their high temperature properties including oxidation resistance, thermal shock behavior and ablation resistance; secondly, researching on the influences of cooling media, reactive products formed at high temperature, and microstructures on thermal shock behavior of Ti2AlC and Cr2AlC; thirdly, investigating the contributions of ablation products, formation of liquid, oxidation layer, microstructure and second phases to the enhanced ablation resistance. The main purpose of this project is to elucidate the mechanism of the thermal shock resistance of MAX ceramics which has resisted interpretation for about 17 years, and to further reveal the mechanism of their ablation resistance. It is reasonable to believe that creative results can be achieved by performing this project. The present study is beneficial to promote the applications of MAX phases in oxidizing and high temperature environments.